Radiation therapy is used to treat various malignant tumors, either preoperatively, as adjuvant therapy after surgery, as primary therapy for patients unable to tolerate surgery, or to treat recurrences after surgery. Patients undergoing radiation therapy may receive external beam treatment, brachytherapy, or both. Brachytherapy is a term used to describe the short distance treatment of cancer with radiation. This type of treatment typically involves placing the radiation directly into or near the tissue to be treated. The radiation dose may then be delivered over a short period of time (temporary implants) or over the lifetime of the source to a complete decay (permanent implants).
Brachytherapy may be divided into two main classes: intracavitary and interstitial. With intracavitary brachytherapy, the radiation sources are placed within a body cavity close to the affected tissue. In interstitial brachytherapy, the radiation sources are implanted within a volume of tissue. Positioning of the radiation sources is an important aspect of brachytherapy. In order to effectively deliver radiation to the target tissue while helping to minimize exposure (and radiation damage) of surrounding healthy or normal tissue, the radiation sources must be properly positioned during the entire course of treatment.
Various types of brachytherapy applicators have been developed for delivering radiation. In the gynecologic field, an exemplary development was the Fletcher-Suit cervical applicator. This applicator consists of a central tube (tandem) and lateral capsules (ovoids or colpostats). The lateral colpostats provide intravaginal positioning while the central tandem traverses the vaginal canal to project into the cervix. Although the Fletcher-Suit applicator has been widely used, maintaining its position in situ can be difficult due to their weight and the difficulty of ensuring a secure connection between the colpostats and tandem. Other brachytherapy applicators have been developed, e.g., the Miami Vaginal Applicator (Nucletron BV, Veenendaal, NL). However, they can be uncomfortable and/or difficult to insert due to their rigidity and incapability of accommodating variations in anatomy, e.g., variations in the size, shape, and orientation of the uterus among patients, or postoperative distortions in anatomy.
Given the importance of brachytherapy in the treatment of cancer, brachytherapy applicators having physical and/or functional characteristics that help optimize radiation delivery to target tissues while minimizing exposure to healthy or normal tissues would be useful. Applicators that can be easily and securely positioned within the body would be desirable. Additional applicator designs, e.g., applicators capable of conforming to tissue surfaces and accommodating variations in anatomy would also be useful.